The invention starts with a device for mounting an electric motor in a manner that isolates vibrations.
Electric motors, such as those that are used in fans of heating and/or air conditioning systems in motor vehicles, are as a rule vibrationally isolated vis-à-vis the vehicle in order to avoid or reduce the transmission of structure-borne noise from the motor or the fan unit to the body and thus to the passenger compartment of the vehicle.
Running noise from the electric motor and run-induced vibrations that are generated, e.g., by an imbalance in a fan wheel that must be driven, are transmitted as a result to a high degree to the housing and lead to the undesirable development of noise.
Common fastening methods for these types of motors consist of inserting the complete motor in a plastic housing or a housing made of metal, which is provided with a flange for connection to the air conditioner. Normally, rubber or correspondingly formed rubber elements are inserted between the motor and the motor housing or in the flange in order to dampen the stimulation of vibrations of the air conditioner or the body and to suppress noises in the passenger compartment of the vehicle that are annoying to the driver or his passengers.
In the case of elastic isolating elements, which, on the one hand hold the electric motor on support areas and, on the other hand, are supposed to provide dampening, these opposing requirements lead to the isolating element being pre-tensioned for example. Since the dampening of the vibrations therefore occurs via flexing work in the isolating elements, no optimal isolation is possible.
During operation of the electric motor, tangential torsional vibrations as well as vibrations in the radial and axial direction, among other things, are generated in the main direction of stimulation of vibrations of the motor. For isolation between the motor and a receptacle housing for the motor, which is supposed to simultaneously serve as an isolating housing, this means that the isolation in the tangential direction must be particularly soft, but clearly more rigid in the axial direction or radial direction.
There are currently several variations in practical use of arranging the isolating elements between the housing flange or between the motor and the motor housing in order to achieve vibrational isolation of the electric motor vis-à-vis the motor housing and as a result vis-à-vis the body.
Thus, for example DE 43 34 124 A1 discloses a device to accommodate an electric motor, which achieves an effect that is particularly low in vibrations and therefore noise dampening, in that at least one elastic dampening element is arranged between the inner walls of this receptacle device and the outer walls of the motor housing that face these, and the dampening element is supported on the facing walls of the receptacle device and the motor housing.
The elastic dampening elements, which are correspondingly formed rubber elements in a preferred embodiment of the device in DE 43 34 124 A1, means increased assembly and material expenses, which unnecessarily increases the costs of such a device.
Using elastic balls, made preferably of an elastomer, is known from EP 0 682 396 A2 in order to isolate two components from one another. In doing so, the balls are each accommodated in an ellipsoidal cavity so that a certain degree of free rotational movement is made possible for the balls. Each of the components has these types of cavities, which are attached in such a way that the cavities of both components lie opposite from one another in a built-in state.
Typically the electric motor is put in an adapter housing on which corresponding holding means are provided to accommodate the isolation bodies. The unit made of up electric motor, adapter and isolation means is then inserted into a motor housing or another functional housing.
An isolating device for actuators, such as electric motors for example, is known from DE 199 42 840 A1, in which a single-piece or multi-piece isolation housing is connected with a functional housing in such a way that a plurality of isolating elements arranged in pairs between the housings is arranged and respectively fixed by a holding element, whereby the actuator acts on the holding elements.
Disadvantageous in the case of the arrangement in accordance with DE 199 42 840 A1 is the expensive construction, which because of the numerous components requires clearly increased assembly expenditures and thus also cost expenditures for isolating the vibrations of an electric motor.